bcachefs: Start gc, copygc, rebalance threads after initing writes ref

This fixes a bug where copygc would occasionally race with going
read-write and die, thinking we were read only, because it couldn't take
a ref on c->writes.

It's not necessary for copygc (or rebalance, or copygc) to take write
refs; they could run with BCH_TRANS_COMMIT_nocheck_rw, but this is an
easier fix that making sure that flag is passed correctly everywhere.

Signed-off-by: Kent Overstreet <[email protected]>

diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 24672bb31cbe9c479964dffe1d1b979dd66013c7..14f4eff421cf7498a79859bbeed6f231a6f12b88 100644 (file)
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -423,6 +423,18 @@ static int __bch2_fs_read_write(struct bch_fs *c, bool early)
                bch2_dev_allocator_add(c, ca);
        bch2_recalc_capacity(c);
 
+       set_bit(BCH_FS_RW, &c->flags);
+       set_bit(BCH_FS_WAS_RW, &c->flags);
+
+#ifndef BCH_WRITE_REF_DEBUG
+       percpu_ref_reinit(&c->writes);
+#else
+       for (i = 0; i < BCH_WRITE_REF_NR; i++) {
+               BUG_ON(atomic_long_read(&c->writes[i]));
+               atomic_long_inc(&c->writes[i]);
+       }
+#endif
+
        ret = bch2_gc_thread_start(c);
        if (ret) {
                bch_err(c, "error starting gc thread");
@@ -439,24 +451,16 @@ static int __bch2_fs_read_write(struct bch_fs *c, bool early)
                        goto err;
        }
 
-#ifndef BCH_WRITE_REF_DEBUG
-       percpu_ref_reinit(&c->writes);
-#else
-       for (i = 0; i < BCH_WRITE_REF_NR; i++) {
-               BUG_ON(atomic_long_read(&c->writes[i]));
-               atomic_long_inc(&c->writes[i]);
-       }
-#endif
-       set_bit(BCH_FS_RW, &c->flags);
-       set_bit(BCH_FS_WAS_RW, &c->flags);
-
        bch2_do_discards(c);
        bch2_do_invalidates(c);
        bch2_do_stripe_deletes(c);
        bch2_do_pending_node_rewrites(c);
        return 0;
 err:
-       __bch2_fs_read_only(c);
+       if (test_bit(BCH_FS_RW, &c->flags))
+               bch2_fs_read_only(c);
+       else
+               __bch2_fs_read_only(c);
        return ret;
 }